US 3208232 A
Abstract available in
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Description (OCR text may contain errors)
Sept. 28, 1965 s. L. MADISON ETAL 3,208,232
REFRIGERATING APPARATUS Filed Oct. 4, 1963 2 Sheets-Sheet l mm 6 0 0 4 Wm) WLM v MM v r l lV/J r THEIR ATTORNEY Sept. 28, 165 s. L" MADISON ETAL 3 REFRIGERATING APPARATUS Filed Oct. 4, 1963 2 Sheets-Sheet 2 KP I Q g 8 3 8 g INVENTOR5 "3 1' m N SHANNON L. MADISON scmovas 3 N LL DAVID L.JONs,.JR.
THEIR ATTORNEY United States Patent 3,208,232 REFRIGERATING APPARATUS Shannon L. Madison and David L. Jones, Jr., Rochester, N .Y., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Oct. 4, 1963, Ser. No. 313,922 1 Claim. (Cl. 62-77) This invention relates to refrigerating apparatus and more particularly to refrigerating systems assembled at the place of installation from major components.
When the major components of a refrigerating system are assembled at the place of installation, the life and performance thereof and the freedom from failure and servicing depend almost entirely on the care exercised by the installer in connecting the tubing between the units. Heretofore this has required the services of a trained refrigeration mechanic and often a vacuum gauge, a vacuum pump, a charging cylinder, a weighing scale and a charging restricter. All these things increase the expense of installation and therefore discourage sales of this type of system.
It is an object of this invention to provide a method of, and apparatus for connecting together the units of a refrigerating system and establishing the proper refrigerant charge in the system which is much quicker and which does not require a refrigeration technician, vacuum pump, vacuum gauge, or any charging apparatus such as a refrigerant bottle, charging cylinder, a weighing scale, or a charging restricter.
It is another object of this invention to provide a method of, and apparatus for connecting together with tubing a charged condensing unit and an evaporator in which the proper reference charge is established by bleeding refrigerant through a known orifice for a time determined by the pressure of the refrigerant and the length of tubing connecting the outlet of the condensing unit and the inlet of the evaporator.
These and other objects are obtained in the form shown in the drawings in which the refrigerant condensing unit is provided with a combination shutoff valve and gauge connections at both its inlet and its outlet. It is shipped with a charge of refrigerant and lubricant which is in excess of its operating requirements. Both the condensing unit and the evaporator are shipped separately and placed in their most desirable locations at the place of install-ation. A liquid line tube is connected to and extended from the valve at the outlet of the condensing unit to the inlet of the evaporator where it is properly connected. A suction line tube is connected and extended from the valve at the inlet of the condensing unit to the outlet of the evaporator where it is properly connected. A service manifold gauge and valve set is then connected to the two gauge connections of the valves at the inlet and the outlet of the condensing unit. The middle connection of the service manifold valve and gauge set is provided with a flare cap having a calibrated orifice of known properties.
The valve at the outlet of the condensing unit is opened until the evaporator as well as the liquid and suction line tubes are filled to a pressure of about 40 p.s.i. gauge. The connections as well as the entire system is then tested for leaks. In the absence of leaks, the valve at the outlet of the condensing unit is opened slightly and the length of the liquid line tubing connecting the outlet of the condensing unit and the inlet of the evaporator is measured. The liquid line pressure gauge is also measured. From a chart there is determined a bleed cycle time in seconds corresponding to the measured length of liquid line tubing and to the liquid line pressure. Following this, the valve on the suction side of the service manifold valve and gauge set is opened for the time corresponding to the bleed cycle time read 'on the chart and then closed immediately. After this the valves at the outlet and inlet of the condensing unit are moved to their normal operating position, the service manifold is removed and the gauge connections are capped. After the unit is connected to electrical supply, it is ready for operation.
Further objects and advantages of the present invention will be apparent from the following description, reference being made to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.
In the drawings:
FIGURE 1 is a perspective view of one form of refrigerating system to which our invention may be applied. FIGURE 2 is an enlarged perspective view of the outlet valve of the condensing unit.
FIGURE 3 is an enlarged perspective view of the inlet valve of the condensing unit.
FIGURE 4 is a vertical sectional view of the valve shown in FIGURE 2 but is also typical of the valve shown in FIGURE 3.
FIGURE 5 is a sectional view showing the flare cap with the calibrated orifice which is applied to the service manifold as shown in FIGURE 1.
FIGURE 6 is a bleed cycle time chart for determining the bleeding time necessary to establish the proper refrigerant charge in the refrigerating system.
Referring now more particularly to FIGURE 1, there is indicated a refrigerant condensing unit 20 including a sealed motor compressor unit 22 having connected to it an inlet conduit 24 extending to a suction line valve 26 which is closed to keep the refrigerant charge from escaping from the inlet conduit 24. Also connected to the sealed unit 22 is a discharge conduit 28 connecting with the condenser 30 which has its outlet conduit 32 connected to the liquid line valve 34 which is shut to maintain the refrigerant charge in the unit and to prevent its escape from the outlet conduit 32. This unit is charged with lubricant and refrigerant to a weight sufficiently above the basic normal operating requirements of this system to provide an excess for purging and for filling the liquid line tubing to the evaporator when this connection does not exceed 50 feet. This charge may, for example, develop or more p.s.i. gauge pressure as indicated by the chart in FIGURE 6.
The condensing unit 20 as well as the evaporator unit 36 are provided with suitable bases and separately installed at the location as desired. The evaporator unit is shipped with a charge of refrigerant sufficient to prevent foreign matter and moisture from getting into the tubes. It is shipped with caps over its connections. The condensing unit is also shipped with caps over the connections 46 and 40 of the valves 26 and 34. The dehydrated refrigeration grade copper tubing need not be shipped with the units but may be purchased from local suppliers. It is extended from the condensing unit 20 to the evaporator 36 as directly as possible. The liquid line tubing 38 is connected to the outlet connection 40 of the valve 34 at one end and at its opposite end to the inlet connection 42 of the evaporator unit 36. The suction line tubing 44 is connected to the inlet connection 46 of the valve 26 at one of its ends and at its other end to the outlet connection 50 of the evaporator unit 36.
A service manifold 52 is then connected by the conduits 54 and 56 to the gauge connections 58 and 60 of the valves 34 and 26. This service manifold 52 is provided with a liquid line gauge 62 and a suction line gauge 64. The service manifold 52 at its opposite ends is provided with a liquid valve 66 which controls the flow from the conduit 54- to the central portion of the manifold 52 which is provided with a middle connection 68. The opposite end of the service manifold 52 is provided with a suction side valve 70 which controls the flow from the conduit 56 to the middle connection 68 of the service manifold 52. This middle connection 68 is provided with a flare cap 72 having a calibrated orifice 74. Prefer-ably this is shipped to the installation with the units so as to make certain that the proper sized calibrated orifice is used.
The valve 34 is specifically illustrated in FIGURE 4 in the closed position in which it is normally shipped as a part of the condensing unit 20. It includes a valve stem 76 having an intermediate threaded portion 7 8 and at the opposite end a double seating valve 80 which during shipping is seated upon the lower seat 82 to hold the refrigerant charge in the condensing unit 20. During normal operation of the refrigerating system, it is seated against the upper seat 84 which allows free flow of refrigerant from the outlet conduit 40 of the condensing unit 20 to the liquid line tubing 38. When the double seating valve 80 is adjusted to an intermediate position or when it is seated on the lower seat 82, access is provided through the passages 86 and 88 to the gauge connection 58. This permits flow of refrigerant through the conduit 54 to the service manifold 52. The valve 26 is similarly constructed.
T o establish the proper refrigerant charge in the system, the liquid line valve 34 is first opened slightly until the suction line gauge 64 indicates approximately 40 p.s.i. gauge pressure after which the valve 34 is closed. The valve 26 is in the position at this time to allow flow to the gauge 64. The system is then checked for leaks at all the joints. In the absence of leaks, the service line valve 34 is opened about one-fourth turn and the length of the liquid line tubing 38 is measured and the liquid line pressure gauge 62 is read. From the chart shown in FIG- URE 6, the bleeding cycle time for the calibrated orifice 74 is read from the column on the left opposite the graphical interesection of the liquid line tubing length and the pressure read on the gauge 62. For example, if the liquid line tubing 38 has a length of 20 feet and the gauge 62 has a reading of 100 p.s.i. gauge, these two will intersect on the chart at the point 90. Applying this point 90 to the time scale on the left edge of the chart, indicates a reading of 262 seconds. The valve 70 on the suction side of the service manifold 52 is opened at the same time a count is started on a stop-watch or a watch with a sweep second hand. When the determined time such as 262 sec. has elapsed, this valve 70 is then closed immediately. The proper chargein the system is thereby established. The liquid and suction line service valves 34 and 26 are then seated to their upper positions for the normal position for refrigeration operation.
If required, a condensate drain may then be installed for the evaporator unit 36. The electrical service connections for the condensing unit are then made and the apparatus checked for satisfactory operation. At the conclusion of this checking, the service manifold 52 and its connecting conduits 54 and 56 are removed from the gauge connections of the valves 34 and 26, and these gauge connections are then closed by flare nuts. The installation is thus completed without the use of a vacuum pump, a vacuum gauge, a refrigerant bottle, a weighing scale or a charging restricter. The system requires no expensive expansion valves since a simple restricter may be used. No sight glasses are required to ascertain a liquid level. The system does not require purging with another gas such as nitrogen. The installation can be made inmuch less time than has been previously required. It is estimated that the installation can be made in less than one-fourth the time required to install what previously has been a standard system. The installation is so simple that when proper directions are followed, a trained refrigeration mechanic is not required.
While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.
What is claimed is as follows:
The method of installing and reducing the charge in a refrigerating system comprising a refrigerant evaporator and a separate refrigerant condensing unit charged with lubricant and an excess of refrigerant in which the condensing unit is sealed With valves connected to its outlet and inlet which includes connecting with tubing the inlet and outlet of the evaporator respectively with the valves connected to the outlet and inlet of the condensing unit, measuring the pressure within the condensing unit, measuring the length of the tubing connecting the inlet of the evaporator with the valve connected to the outlet of the condensing unit, connecting an orifice outlet of known size and characteristics to the refrigerating system, and bleeding the refrigerating system through said orifice outlet for a period of time dependent upon the measured pressure within the condensing unit and the measured length of the tubing connecting the inlet of the evaporator and the valve at the outlet of the condensing unit.
References Cited by the Examiner UNITED STATES PATENTS 2,464,563 3/49 Doeg 62292 2,512,090 6/50 Cooper 6277 2,934,915 5/60 Morse 62-77 3,118,463 1/64 Lacart 6277 X OTHER REFERENCES Althouse and Turnquist, Modern Refrigerationand Air Conditioning, Chicago, Goodhearth-Willcox Co. Inc., 1956-TP 492 A43, C. 2.
ROBERT A. OLEARY, Primary Examiner,